1. Field of the Invention
This invention relates to agricultural implements used to apply fertilizer to a subsoil location, and more particularly, to an applicator knife for placing a fluid fertilizer, such as anhydrous ammonia, in a burrow or trench as it is formed by transition of the knife blade through the soil. More specifically, the invention relates to a protective hard metal insert which is secured to the shank of the fertilizer knife or blade in order to form a portion of the leading edge thereof. The insert is especially shaped and fabricated to provide an effective cutting action where stalks, stubble and trash are to be traversed by the fertilizer applicator knife blade during use.
2. Brief Description of the Prior Art
An applicator knife blade employed for depositing or placing anhydrous ammonia in the soil includes a curved shank plate having a pointed lower end which carries at its rear side, an elongated fertilizer tube through which the anhydrous ammonia is caused to flow don the back side of the shank blade to a point of discharge where the fertilizer is discharged into a trench formed by the blade. Typically, the knife blade shank will carry at its leading edge, a protective hard metal insert element which is welded to the leading edge of the shank blade and is configured so as to provide a relatively sharp edge capable of cutting through the soil. The hard metal insert functions to protect the leading side of the shank blade against abrasive wear and deleterious impact with rocks or other abrasive elements in the soil.
In U.S. Pat. No. 4,355,589 assigned to the assignee of the present application, one type of fertilizer applicator knife assembly is illustrated. This fertilizer applicator knife assembly carries a wear insert at the leading side of the knife's shank blade. The insert is made of a very hard, abrasion-resistant metal, such as chromium carbide. It is beveled or tapered to a relatively narrow edge at its front or leading edge so as to provide a cutting action as the knife assembly is forced through the soil during application of the fertilizer.
An improved form of fertilizer applicator knife assembly is shown in my co-pending application Ser. No. 699,169 of which the present application is a continuation-in-part.
Other types of hard metal inserts for similar usage at the leading side of a fertilizer applicator knife blade are illustrated in Smith et al U.S. Pat. No. 4,132,181; Stump U.S. Pat. No. 4,201,402; Williams U.S. Pat. No. 4,033,721; Horton U.S. Pat. No. 3,259,087; and Johnston U.S. Pat. No. 2,684,617.